If someone thought something defied the laws of physics, it would either be because they didn't understand those laws properly, or because they'd misinterpreted whatever they'd perceived.
–
FumbleFingersJun 13 '13 at 22:13

2

@FumbleFingers or perhaps they were using hyperbole? Language is not bound by reality, otherwise how would we use it to express the unreal?
–
congusbongusJun 14 '13 at 0:52

@CongXu, I think that's a good point, but what if we are talking about the title of an online news article, which is presumed to be factual? Or is hyperbole in the title of an online news article just considered par of the course :-)
–
David HammondJun 14 '13 at 1:02

@Cong Xu: Creative/loose use of language is perfectly possible. But presumably OP's first sentence should be read as meaning he's not interested in non-literal usages. p.s.w.g.'s my new model of quantum theory defies the laws of physics is a brave attempt to slip in a "literal" version, but it doesn't really work (the audience would probably assume the speaker was admitting his theory was no good, since it didn't match reality).
–
FumbleFingersJun 14 '13 at 1:05

@fumbleFingers Fair enough. I think what you're ultimately saying is that if you're speaking literally then the answer is no, you can't defy the laws of physics.
–
David HammondJun 14 '13 at 2:32

In most cases, the idiom defying the laws of physics appears to be using the second sense of the word. Consider these examples:

this superliminal spaceship defies the laws of physics

In this case, it appears that the phrase is to describe something which defies the conventional notion of physical reality. If it truly were possible to build such a spaceship, it wouldn't violating the fundamental nature of the universe, but it would change our understanding of it.

this gymnast's performance defies the laws of physics

In this case, it's a bit of hyperbole. It's well understood that the gymnast is not doing something truly physically impossible—unless she's levitating—but is merely presenting a performance that is so physically demanding, the speaker was amazed.

There are also contexts where it might be using the third sense of the word, for example:

my new model of quantum theory defies the laws of physics

Here, the speaker is means that his model presents a substantial challenge to the currently accepted laws of physics. In the future the new model might be accepted in favor of the current laws. Of course, the model is just an idea with no physical form, so it cannot do any defying by itself.

the action scenes in that movie defy the laws of physics

Here, the action scenes are described pejoratively as too unrealistic to be believable. The director is simply disregarding the laws of physics for the purpose of entertainment.

Hmm. I disagree that we're talking about the the 2nd definition. In your examples you are not issuing a challenge to the spaceship, the gymnast, etc.
–
David HammondJun 14 '13 at 0:49

2

@David Hammond: You have it the wrong way round - the spaceship, the gymnast, etc. are issuing a challenge to the laws of physics. Certainly if you accept p.s.g.w.'s "quantum theory" case, I think you'd have to read that as "challenging" (unless you see it as idiomatically unavoidably being an admission of the theory's demonstrable flaw).
–
FumbleFingersJun 14 '13 at 1:07

@FumbleFingers, I don't think so. If you go by the 2nd definition, then "this superliminal spaceship defies the laws of physics" means that the spaceship is challenging the laws of physics to do something impossible. The laws of physics are what define whether something as possible or not, so that doesn't make sense.
–
David HammondJun 14 '13 at 1:13

1

@@David Hammond: Duh. That's why I closevoted as NARQ. You're simultaneously postulating the existence of a superliminal spaceship, and saying the laws of physics limit reality. But by the laws of physics (as we currently understand them) obviously that ship can't even exist to do any challenging. (If it did exist nevertheless, I suppose it would be challenging the laws of physics to explain its "existence"! :)
–
FumbleFingersJun 14 '13 at 1:20

"First, let's take a look at the definition of defy": That's the OP's job.
–
KrisJun 14 '13 at 6:07

I could defy or challenge the laws of physics to operate in a particular circumstance, such as by jumping off a tall building and expecting to float to the ground without getting hurt. In such a challenge or act of defiance, I would lose to those laws. One may certainly defy civil laws and in some cases you will get away with doing so, but defying the laws of physics in the wrong way can get you in real trouble. Still, you may defy them if you want. As a physicist you would expect that subjecting material to pressure would result in a material with a higher density if only when under that pressure. In fact in the case of the experiment that started this discussion, stating that the result "defied the laws of physics" is shorthand for the fact that the material that resulted was less dense than what they started with. Of course, the material became porous and if you measured the true density of the material with the pores emptied of the fluid, the density may or may not have been lower, but the factor of two difference would surely not have obtained. Different physical "phases" or rearrangement of the molecules often results in variations in density but in this case the material had known porosity-that, in fact, was the main benefit that may give the material practical value.

So, what particular definition of "defy" are you using here?
–
David HammondJun 14 '13 at 11:33

In my original post on FB wherein I differed with Mark, I actually was using the word as in definition 2 above, but this was actually a bit of a play on the word as used in the headline that started all this. In my paragraph above, the first part uses this definition, too, but I acknowledge that the use in the referenced headline does not quite do the same. That is why I used the term "shorthand" above. I still think the headline meets a very loose standard and does not demonstrate "ignorance" as was stated in the original post on FB.
–
Jim HammondJun 14 '13 at 15:50

That makes sense to say an implicit challenge is being issued to the laws of physics "to operate", as you say. I think I was just confused about whether, in the absence of an explicit challenge to do something, the 3rd definition would apply.
–
David HammondJun 15 '13 at 21:38